Goodwill and Intangible Assets - Goodwill (Details)	3 Months Ended
	Apr. 01, 2017 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 188,010,000
Foreign currency translation	175,000
Goodwill, ending balance	188,185,000
Goodwill impairment	0
Cascade Microtech
Goodwill [Roll Forward]
Goodwill, ending balance	158,141,000
MicroProbe Inc.
Goodwill [Roll Forward]
Goodwill, ending balance	30,700,000
Probe Cards
Goodwill [Roll Forward]
Goodwill, beginning balance	172,482,000
Foreign currency translation	0
Goodwill, ending balance	172,482,000
Systems
Goodwill [Roll Forward]
Goodwill, beginning balance	15,528,000
Foreign currency translation	175,000
Goodwill, ending balance	$ 15,703,000